Revert "mptcp: drop legacy code"

This reverts commit ccd4c33. According to Paolo, this one is causing issue #356 and indirectly #370. Closes: #356 Signed-off-by: Matthieu Baerts <[email protected]>
multipath-tcp · Mar 9, 2023 · 4ef602b · 4ef602b
1 parent bed92cb
commit 4ef602b
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Showing 2 changed files with 10 additions and 4 deletions.
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
@@ -988,7 +988,12 @@ static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
 	mptcp_subflow_fully_established(subflow, mp_opt);
 
 check_notify:
-	if (likely(subflow->pm_notified))
+	/* if the subflow is not already linked into the conn_list, we can't
+	 * notify the PM: this subflow is still on the listener queue
+	 * and the PM possibly acquiring the subflow lock could race with
+	 * the listener close
+	 */
+	if (likely(subflow->pm_notified) || list_empty(&subflow->node))
 		return true;
 
 	subflow->pm_notified = 1;

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
@@ -1871,10 +1871,11 @@ static void subflow_ulp_release(struct sock *ssk)
 
 	sk = ctx->conn;
 	if (sk) {
-		/* if the subflow has been closed by the TCP stack, keep
-		 * the ctx alive, will be freed by __mptcp_close_ssk()
+		/* if the msk has been orphaned, keep the ctx
+		 * alive, will be freed by __mptcp_close_ssk(),
+		 * when the subflow is still unaccepted
 		 */
-		release = ctx->disposable;
+		release = ctx->disposable || list_empty(&ctx->node);
 
 		/* inet_child_forget() does not call sk_state_change(),
 		 * explicitly trigger the socket close machinery